Coefficient of static friction on a ramp?

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To find the coefficient of static friction between the block and the plank, the problem involves analyzing a triangle formed by the ramp's height and length. The relevant equations include F = ma and fs = mus x FN, where FN is the normal force. The mass of the block is not provided, but it can be treated as an unknown "m" to simplify calculations, as it will cancel out in the algebra. The discussion emphasizes working symbolically to derive the solution. Understanding the application of these equations is crucial for solving the problem effectively.
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Homework Statement


A small block sits at the midpoint of a 2.0 m plank lying on a level floor. A student slowly raises one end of the plank until the block starts to slide. At that instant, the raised end is 0.55 m above the floor. Find the coefficient of static friction between block and plank.

Homework Equations


F = ma
fs = mus x FN

The Attempt at a Solution



so i turned it into a triangle and the sides are 1.9, .55, 2.0
theres no mass given so I'm not sure how to even begin to find the force of friction or force normal
 
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Work symbolically. Leave the mass as an unknown "m" and work through the algebra. You should find that the m will cancel out along the way.
 
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gneill said:
Work symbolically. Leave the mass as an unknown "m" and work through the algebra. You should find that the m will cancel out along the way.
i don't understand. using what equation?
 
katie beisel said:
i don't understand. using what equation?
What equations would you apply if the mass were given?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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